The present invention relates to a parachute device for a divisible shell, for example a shell comprising an active body in the form of an illuminating charge, which after separation from the shell is to be slowed in its descent to the ground.
After firing a shell containing an illuminating charge, the illuminating charge is released from the shell at a predetermined height, a parachute being deployed and slowing the descent of the illuminating charge to the ground. At the same time the bottom part of the shell, referred to as the shell base, is released, this being allowed to fall freely to the ground. The shell base, which weighs approximately 0.8 kg attains a velocity of more than 100 m/s, which harbors a safety risk to persons on the ground.
It is desirable to provide a parachute device designed so that both the illuminating charge and the shell base are slowed in their descent to the ground.
It is also desirable to provide a parachute device having few constituent parts.
Thus, according to an aspect of the present invention, a parachute device has been produced for a divisible shell, comprising an active body and a shell base.
The invention, according to an aspect thereof, is characterized in that the parachute device comprises two parachutes, a first, main parachute connected to the active body of the shell by parachute lines, and a second parachute connected to the base of the shell.
According to a second embodiment of the parachute device according to an aspect of the invention, the second parachute constitutes the packing chute for the main parachute, wherein the second parachute comprises a front, open part, referred to as the base, and a rear part, referred to as the chute, wherein the chute is connected to the shell base by a fixing plate and a fixing screw arranged on the inside of the chute, wherein the fixing plate is fixed to the inside of the shell base by the fixing screw, so that the chute is clamped firmly between the fixing plate and the shell base.
According to a third embodiment of the parachute device according to the invention the base comprises a stretchable, elastic line stitched into a seam around the outer edge of the base, wherein the chute comprises folds with tear seams designed to rupture at a given load, and wherein the chute also comprises drag lines fixed between the outer edge of the base and the inside of the chute, so that the base is slowed due to the air resistance after separation from the shell and deploys at the same time that the shell base, owing to its inertia, moves towards the chute, so that the chute is turned inside out and forms the second parachute.
The invention, according to an aspect thereof, affords a series of advantages and effects, the most important of which are:
A parachute device comprising two parachutes means that both the active body and the shell base can be slowed in their descent to the ground, which affords an additional safeguard and means that the extent of the risk can be reduced.
Using the second parachute as a packing case for the main parachute provides a parachute device having few parts and a low weight.